I'm not sure if this is the right place to post this, so please advise if this needs to be moved.
The question deals with 4 mis-matched solar panels on an RV roof. Yes, it is a bad design, but the RV mfg is no longer in business, so there you go.
I am somewhat knowledgeable on solar array design for a "normal" system. In simple systems, modules get arranged in strings, which get tied together in parallel, and then brought into an inverter, The number of modules in each string needs to be the same or inefficiencies develop quickly. Each panel design has a short circuit current rating and an open circuit voltage rating. The inverter than attempts to find the maximum power point where current draw and voltage output of the array produce the most wattage for the amount of sunlight at the time
Now to the question. There are 4 panels on the RV roof. 1 large (6 cells wide, 10 cells long), 2 identical mid-size panels (4 cells wide, 9 cells long), and 1 small panel (2 cells wide, 6 cells long). I cannot find part numbers or specs on the panels due to them being up against the RV roof. I believe (a guess, but that’s all I have to go on at this point) that they are wired as:
LARGE -> 2 MIDSIDE in parallel -> SMALL
since open circuit voltage is around 100V DC. The quoted output of this arrangement is 470W, which likely means that the RV manufacturer took the absolute max wattage rating of each panel and added them up. As installed, on a cool (better for solar output) bright sunny day with sun directly overhead, output has never exceeded 100W. I don’t expect anything near 470W, but certainly more than 100W.
With this mis-match of panels, is there a way to wire this up so the solar inverter has a chance of finding a maximum power point? Thanks.
The question deals with 4 mis-matched solar panels on an RV roof. Yes, it is a bad design, but the RV mfg is no longer in business, so there you go.
I am somewhat knowledgeable on solar array design for a "normal" system. In simple systems, modules get arranged in strings, which get tied together in parallel, and then brought into an inverter, The number of modules in each string needs to be the same or inefficiencies develop quickly. Each panel design has a short circuit current rating and an open circuit voltage rating. The inverter than attempts to find the maximum power point where current draw and voltage output of the array produce the most wattage for the amount of sunlight at the time
Now to the question. There are 4 panels on the RV roof. 1 large (6 cells wide, 10 cells long), 2 identical mid-size panels (4 cells wide, 9 cells long), and 1 small panel (2 cells wide, 6 cells long). I cannot find part numbers or specs on the panels due to them being up against the RV roof. I believe (a guess, but that’s all I have to go on at this point) that they are wired as:
LARGE -> 2 MIDSIDE in parallel -> SMALL
since open circuit voltage is around 100V DC. The quoted output of this arrangement is 470W, which likely means that the RV manufacturer took the absolute max wattage rating of each panel and added them up. As installed, on a cool (better for solar output) bright sunny day with sun directly overhead, output has never exceeded 100W. I don’t expect anything near 470W, but certainly more than 100W.
With this mis-match of panels, is there a way to wire this up so the solar inverter has a chance of finding a maximum power point? Thanks.